Recent trends in the advancement of surgical technology have tended toward less invasive procedures in order to reduce trauma to the patient. For example, an important advancement in the area of cardiac surgery is represented by U.S. Pat. No. 5,571,215, and copending patent application Ser. No. 08/281,981, which describe systems for arresting the heart, maintaining circulation of oxygenated blood in the patient and carrying out surgical procedures, such as coronary artery bypass graft (CABG) surgery or heart valve replacement surgery, on the heart.
Another recent therapy is known as Transmyocardial revascularization (TMR) which is a treatment for patients suffering from medically refractory angina pectoris with coronary artery anatomy unsuitable for treatment with more conventional coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. Typically, a high-energy laser is employed to create 20-30 passageways or channels in an ischemic myocardium which penetrate therethrough into the left ventricular chamber. In theory, the channels act as conduits to perfuse oxygenated blood from the left ventricle into the extensive intramyocardial vascular plexus. In essence, at the immediate treated site of the myocardium, the epicardial vasculature is bypassed.
Yet another new technique is molecular enhancement of endothelial cell motility and angiogenesis. One such molecular enhancement is the application of Vascular Endothelial Growth Factors (VEGF) to further stimulate additional angiogenesis. VEGF is a selective mitogen for vascular endothelial cells which has been shown to accelerate endothelial repaving, and attenuate intimal hyperplasia after in vivo arterial injury. D. Weatherford, J. Sackman, T. Reddick, M. Freeman, S. Stevens and M. Goldman, Vascular endothelial Growth Factor and Heparin in a Biological Glue Promotes Human Aortic Endothelial Cell Proliferation with Aortic Smooth Muscle Cell Inhibition, SURGERY, August 1996, 433-439. Vascular endothelial growth factor is one of the proangiogenic molecules which include members of the fibroblast growth factor family, transforming growth factor-.beta., tumor necrosis factor-.alpha., platelet-derived growth factors, as well as other factors. These soluble molecules exert their angiogenic stimuli by coupling to the cell surface receptor and trigger the functions within the endothelial cells through signaling cascades. Engler, D., Use of Vascular Endothelial Growth Factor for Therapeutic Angiogenesis, CIRCULATION, 1996;94:1496-1498.